1. Field of the Invention
This invention relates to amorphous metal alloys, and, more particularly, to high strength, low density compositions in the beryllium-titanium-zirconium system.
2. Description of the Prior Art
Investigations have demonstrated that it is possible to obtain solid amorphous materials from certain metal alloy compositions. An amorphous material substantially lacks any long range order and is characterized by an X-ray diffraction profile in which intensity varies slowly with diffraction angle. Such a profile is qualitatively similar to the diffraction profile of a liquid or ordinary window glass. This is in contrast to a crystalline material which produces a diffraction profile in which intensity varies rapidly with diffraction angle.
These amorphous metals exist in a metastable state. Upon heating to a sufficiently high temperature, they crystallize with evolution of heat of crystallization, and the X-ray diffraction profile changes from one having amorphous characteristics to one having crystalline characteristics.
Novel amorphous metal alloys have been disclosed and claimed by H. S. Chen and D. E. Polk in U.S. Pat. No. 3,856,513, issued Dec. 24, 1974. These amorphous alloys have the formula M.sub.a Y.sub.b Z.sub.c where M is at least one metal selected from the group of iron, nickel, cobalt, chromium and vanadium, Y is at least one element selected from the group consisting of phosphorus, boron and carbon, Z is at least one element selected from the group consisting of aluminum, antimony, beryllium, germanium, indium, tin and silicon, "a" ranges from about 60 to 90 atom percent, "b" ranges from about 10 to 30 atom percent and "c" ranges from about 0.1 to 15 atom percent. These amorphous alloys have been found suitable for a wide variety of applications, including ribbon, sheet, wire, powder, etc. Amorphous alloys are also disclosed and claimed having the formula T.sub.i X.sub.j, where T is at least one transition metal, X is at least one element selected from the group consisting of aluminum, antimony, beryllium, boron, germanium, carbon, indium, phosphorus, silicon aand tin, "i" ranges from about 70 to 87 atom percent and "j" ranges from about 13 to 30 atom percent. These amorphous alloys have been found suitable for wire applications.
At the time these amorphous alloys were discovered, they evidenced mechanical properties that were superior to then known polycrystalline alloys. Such superior mechanical properties included ultimate tensile strengths of up to 350,000 psi, hardness values (DPH) of about 650 to 750 kg/mm and good ductility. Nevertheless, new applications requiring improved magnetic, physical and mechanical properties and higher thermal stability have necessitated efforts to develop further compositions. More specifically, there remains a need for high strength, low density material suitable for structural applications.